In certain designs of hand held spray guns, the gun includes a body and a barrel which are attached together in a manner which permits removal of the barrel from the body. The barrel may be removed from the body for various reasons. For example, it may be necessary to disassemble the spray gun for major cleaning of internal fluid passages and/or for replacement of worn parts. In hand held electrostatic spray guns, at least a portion of the high voltage power supply may be located in a chamber extending between the barrel and the gun body. Disassembling the barrel from the body provides access for servicing such power supply components. Further, U.S. Pat No. 4,598,871 teaches that an electrostatic spray gun can be provided with multiple barrels for adapting the gun to different coating applications. One barrel and attached nozzle assembly is designed for air atomization of paint. Another barrel and nozzle assembly is designed for hydrostatic or airless atomization of paint and still a third barrel and nozzle assembly may be designed for applying fluidized powder coatings. In the spray gun shown in this patent, all air and fluid connections are made directly to the barrel and do not go through the gun body. A fluid valve actuator on each barrel is located to engage a trigger on the gun body. A high voltage cable projecting from the gun body extends into and makes electrical contact with components in the attached barrel.
To reduce the weight and the pull from hoses attached to the barrel end of the gun and to improve the balance of the gun, it is preferable to have the electrical supply cables and at least the air supply hose connected to the gun handle. Various connections must be made between the barrel and the body of a spray gun. A manually actuated trigger typically is mounted on the gun body. When actuated, the trigger moves a needle in an axial direction to open a fluid valve located in the gun barrel. Depending on the design and construction of the spray gun, electrical connections and/or compressed air and/or coating liquid passages must extend from the gun body to the barrel. The manner in which the barrel is removably attached to the gun body is critical to prevent air and liquid leakage and to maintain continuity of electrical connections and electrical insulation. Also, the design must facilitate servicing components mounted in the barrel and in the gun body.